A full-size multi-band Yagi delivers serious gain, but it also demands a serious tower and a lot of real estate. Hex beams and cubical quads exist for hams who want real directional gain without going that far.
The hex beam’s folded-wire approach
A hex beam uses folded wire elements strung between spreader arms in roughly a hexagonal shape, delivering a compact, lightweight antenna that still produces real forward gain and front-to-back ratio on multiple bands from a single feed point. Because the elements fold back on themselves rather than running straight out like a Yagi’s, a hex beam covers a given set of bands in a dramatically smaller turning radius than an equivalent multi-band Yagi, which matters a lot if you’re working with a small tower or a rotator with limited torque.
The cubical quad’s closed loops
A cubical quad uses full-wave loop elements, similar in principle to the delta and horizontal loops covered elsewhere on this site, arranged as a driven element and one or more reflectors and directors, the same basic beam concept as a Yagi but built from loops instead of straight elements. Quads have a reputation for slightly quieter reception and a bit more gain per element than an equivalent Yagi, though the construction is generally more involved, with a spreader frame supporting each loop’s shape.
Which one to actually build
Hex beams have become the more popular choice among hams looking for a compact multi-band beam, mostly thanks to commercial kits that make the build genuinely approachable without custom fabrication. Cubical quads reward hams willing to build and tune their own antenna and want the specific performance characteristics loops bring. For most people wanting directional gain without a full tower commitment, a commercial hex beam kit on a modest tower or roof mount is the more practical starting point.
Related reading: Full-Size Wire Loop Antennas · Antenna Rotators · Antenna Modeling Software